Asked whether he would close all of US borders to migrants, Arpaio adamantly said no.
"I have a chance to continue protecting the people of Arizona and the country, supporting the President, since I supported him since from day one, July 2015", Arpaio told FOX Business' Charles Payne.
Arpaio has been a prominent birther for years, perpetuating false claims that Obama was not born in the USA and questioning the authenticity of his birth certificate.
Birther advocates seized on a book proposal from Obama's days as a young community organizer, which said he was born in Kenya.
"Even if Arpaio loses the primary to McSally, he would have had seven months to push her to the right and define GOP messaging on a host of issues - and not just in Arizona", the Washington Examiner suggests.
Arpaio says he and Trump have been persecuted by the U.S. Department of Justice.
Arpaio said he would accept a Trump endorsement, but he would not seek it.
The former top cop's decision to enter the Senate race came as a surprise to some Democrats, who thought Arpaio's career had ended in 2016. "I don't care if I lose elections or anything", said Arpaio.
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Because of his reputation, Arpaio would be a highly controversial figure running in the Republican primary.
It's also possible that John McCain will give up his Senate seat and get a temporary replacement, which would mean two Arizona Senate contests this year and the possibility that all of this will be reshuffled at some point.
"I think I can make a difference".
In fact, a poll paid for by a local TV station in Arizona and out Wednesday showed exactly that - McSally with 31 percent, Arpaio at 29 and Ward with 25.
This was enforced by Arpaio, who required his deputies to determine the immigration status of anyone breaking the law.
"I'm not going down there to spend 20 years as a senator", he said. What they left out of their hate filled rant were the dozens of Latinos, aka illegal immigrants, who were saved by Arpaio during the sheriff's many anti-smuggling operations.
Arpaio made the announcement Tuesday, injecting new uncertainty and attention into the race that's already among the year's most-watched.